Midterm 1 Flashcards
How did the earth obtain the heat in it’s interior?
From accretion & radioactive decay
What is differentiation/why the interior is layered
The separation of metals and rocks due to density differences
If the inner core is hotter than the outer core, why is only the outer core a liquid?
Inner core is at a higher pressure, and this will shift it into a more dense state, meaning a higher melting point is required relative to the outer core.
What is the cold, strong crust plus the outer, strong part of the mantle called?
Lithosphere
What is warm, weak layer of mantle beneath the rigid plates called?
Asthenosphere
Evidence of continent drifting
- Coastline of America lines up with Europe and Africa’s. Identical volcanic rocks appear on both sides of the Atlantic. Fossil of non-swimmers found in both sides of continents
The Earth’s interior layers and which is thickest/thinnest.
Crust: 0-40km
Mantle: 40 -2890km
Liquid iron outer core: 2890 - 5150km
Solid liquid iron core: 5150 - 6370km
What a solar nebula is?
A cloud of dust and gas particles that are the origin of the solar system.
Where the heat come from that causes new planets to be extremely hot inside.
Planet accretion which comes from ever frequent collisions of rock. These collisions and radioactive elements create the heat that melts the interior.
Plate techtonics
How pieces of a strong lithosphere move around the weak asthenosphere.
Why the inner core is hotter than the outer core yet is a solid.
The inner core has a much greater pressure at the depth closer to the earth’s centre, which results in the core being in a denser state, requiring a greater melting point to turn it into a liquid.
Why hotter mantle beneath the asthenosphere does not flow as easily.
Greater pressure results in a denser state, making it more rigid.
Why few scientists accepted Wegener’s theory of continental drift.
It would require strong oceanic crust to be adjusted for the continents, and the cause of such a strong force would be unknown.
What are Magnetic reversal
Magnetic crystals in lava flow like compasses, showing that the north and south pole switched places.
How we know that our magnetic field has reversed itself many times through Earth’s past.
Changes in polarity over millions of years
The breakthrough observation that led to the theory of plate tectonics.
The magnetic reversals found in oceanic crust seafloor. The ocean crust would form but then move away. This allowed wegner’s theory, to be true as the continents could now drift apart due to ocean crust not being in the way.
Mid-ocean ridge
Magma from far below reaches the surface and cools to form the ocean lithosphere then spreads outwards at the ridge
Subduction zone
Subduction zone is when oceanic plates(excess oceanic crust) is subducted back into the earth’s interior.
Transform plate boundary
A fault where plates slide past each other horizontally
The kind of plate boundary that the San Andreas Fault is.
Transform plate boundary
How plate tectonics may have led to the evolution of whales and dolphins from land mammals.
Over time, as landmasses shifted and environmental pressures changed, certain land mammals, such as the ancestors of whales and dolphins, adapted to aquatic environments, evolving into fully marine species.
How conduction transfers heat.
Conduction transfers heat through the solid through the spread of vibrations on a atomic scale
How convection transfers heat.
Heat transfer through fluid motions of liquids and gases, as well as solids that flow like a liquid.
How radiative heat transfer transfers heat.
There electromagnetic waves through a transparent medium.
The circumstance in which a solid can convect.
If it has a solid liquid structure(crystalline) but can flow like a liquid.
What drives plate tectonics.
Mantle convection, where due to the mid-ocean ridges where magma from below cools into the earth’s lithosphere and spreads out, where eventually in a subduction zone it is sub-ducted back into the earth’s interior.
What causes a magnetic field to be produced.
If the tiny magnetic fields that come from electrons align, a magnetic field will be formed.
How a permanent magnetic is created.
A permanent magnet can be created by temporarily placing a metal(ferromagnetic) into a strong magnetic field
How to make an induced magnetic field generated by an electrical current stronger.
More coils, greater current, more ferromagnetic core
Strong magnetic field for earth’s core
Electrical current from motion of convecting liquid, Spin of earth causing the convection in the outer core, coils spin around iron core
How Earth generates its magnetic field.
Earth’s magnet field acts as a bar magnetic, with the magnetic field lines from the north to south pole.
That the magnetic pole in Earth’s northern hemisphere is actually a south magnetic pole.
Opposite poles attract, so the geographically north pole must be a south magnetic pole to attract the magnet north.
What causes the aurora lights.
Solar wind excites nitrogen and oxygen in the air
How do we know earth is not hollw
Rocks too weak at the higher temperatures and pressure to support voids. Passage of seismic waves show no voids. magnetic field that can only be generated by an liquid iron core. Magnitude of our planet requires a dense continuous interior
The type of volcanic eruption that brings diamonds to the surface
A kimberlite eruption brings the diamonds up to the surface with cooler surrounding rock before the magma can hurt them
About how many total earthquakes of any size occur globally each year.
1.3 million earthquakes